fix(tooltip): tooltip sample not working with keyboard navigation. (#15111)

Author: MartinKamenov

src/material-examples/tooltip-manual/tooltip-manual-example.html

@@ -1,20 +1,20 @@
 <div>
-  <span> Mouse over to </span>
+  <span> Click the following buttons to... </span>
   <button mat-button
-          (mouseenter)="tooltip.show()"
-          aria-label="Button that progamatically shows a tooltip on another button"
+          (click)="tooltip.show()"
+          aria-label="Show tooltip on the button at the end of this section"
           class="example-action-button">
     show
   </button>
   <button mat-button
-          (mouseenter)="tooltip.hide()"
-          aria-label="Button that progamatically hides a tooltip on another button"
+          (click)="tooltip.hide()"
+          aria-label="Hide tooltip on the button at the end of this section"
           class="example-action-button">
     hide
   </button>
   <button mat-button
-          (mouseenter)="tooltip.toggle()"
-          aria-label="Button that progamatically toggles a tooltip on another button to show/hide"
+          (click)="tooltip.toggle()"
+          aria-label="Show/Hide tooltip on the button at the end of this section"
           class="example-action-button">
     toggle show/hide
   </button>
@@ -25,4 +25,4 @@
         matTooltipPosition="right"
         aria-tooltip="Button that displays and hides a tooltip triggered by other buttons">
   Action
-</button>
+</button>